What is the best treatment approach for a patient with infectious diarrhea?

Treatment of Infectious Diarrhea

The cornerstone of infectious diarrhea treatment is oral rehydration solution (ORS) for all patients with mild to moderate dehydration, while empiric antimicrobials should be avoided in most cases of acute watery diarrhea unless specific high-risk features are present. 1

Rehydration: The Foundation of Treatment

Reduced osmolarity ORS is the first-line therapy for mild to moderate dehydration in all age groups, regardless of the underlying pathogen. 1, 2

ORS Administration Protocol

• Administer ORS until clinical signs of dehydration resolve (improved thirst, normal mucous membranes, adequate urine output, normalized orthostatic vital signs). 1, 3
• For patients unable to tolerate oral intake but without severe dehydration, consider nasogastric ORS administration. 1, 2
• Replace ongoing stool losses with ORS until diarrhea completely resolves. 1, 3

When to Use IV Fluids

Reserve isotonic IV fluids (lactated Ringer's or normal saline) exclusively for: 1, 2

• Severe dehydration with hemodynamic instability
• Shock or altered mental status
• Failure of ORS therapy
• Ileus preventing oral intake

Once pulse, perfusion, and mental status normalize with IV therapy, transition immediately to ORS for remaining deficit replacement. 1, 2

Nutritional Management

Resume age-appropriate diet immediately during or after rehydration—do not withhold food. 1, 3 This is a critical point where many clinicians err by unnecessarily restricting diet.

• Continue breastfeeding throughout the illness in infants. 1, 3
• Early realimentation prevents malnutrition and may reduce stool output. 3
• For children 6 months to 5 years in zinc-deficient regions or with malnutrition, provide oral zinc supplementation to reduce diarrhea duration. 1, 2

Antimicrobial Therapy: When to Treat and When to Avoid

The Default Position: No Antibiotics

Empiric antimicrobial therapy is NOT recommended for most patients with acute watery diarrhea without recent international travel. 1, 2 This represents the majority of infectious diarrhea cases seen in clinical practice.

Specific Indications for Antimicrobial Treatment

Consider antimicrobials ONLY in these specific circumstances: 1, 2

• Immunocompromised patients with severe illness (ill-appearing young infants, patients on immunosuppressive therapy). 1, 2
• Bloody diarrhea with presumptive shigellosis (fever, tenesmus, left lower quadrant pain). 1, 2
• Recent international travelers with fever ≥38.5°C or signs of sepsis. 1, 2
• Suspected enteric fever with clinical features of sepsis—these patients require immediate IV broad-spectrum antibiotics after obtaining blood, stool, and urine cultures. 2

Critical Contraindication

Never use antimicrobials in STEC O157 or other Shiga toxin 2-producing E. coli infections—this increases the risk of hemolytic uremic syndrome. 1, 2 This is a potentially fatal complication that can be directly precipitated by antibiotic use.

Treatment Modification

Modify or discontinue antimicrobials once a specific pathogen is identified and clinical response is assessed. 1, 2

Adjunctive Therapies: Use With Extreme Caution

Antimotility Agents (Loperamide)

Loperamide is absolutely contraindicated in children <18 years of age with acute diarrhea. 1, 4 The FDA label emphasizes risks of respiratory depression and cardiac adverse reactions in pediatric patients. 4

For immunocompetent adults with acute watery diarrhea: 1

• Loperamide may be given ONLY after adequate hydration
• Avoid in ANY patient with bloody diarrhea, fever, or suspected inflammatory diarrhea due to risk of toxic megacolon 1, 4
• Do not exceed recommended dosages—higher doses are associated with QT prolongation, Torsades de Pointes, and sudden cardiac death 4
• Avoid in patients taking CYP3A4 inhibitors, CYP2C8 inhibitors, or P-glycoprotein inhibitors, as these dramatically increase loperamide exposure 4

Antiemetics

Ondansetron may be given to children >4 years and adolescents to facilitate oral rehydration when vomiting impairs ORS tolerance. 1 This can be particularly helpful in preventing progression to IV hydration.

Probiotics

Probiotics may be offered to reduce symptom severity and duration in immunocompetent patients, though the evidence quality is moderate. 1, 2 Selection of specific probiotic strains, dosing, and route should be guided by manufacturer recommendations and literature searches. 1

Special Populations and Circumstances

Asymptomatic Carriers

Asymptomatic individuals practicing good hand hygiene in low-risk settings do not require treatment. 1 The exception is asymptomatic carriers of Salmonella Typhi, who may be treated empirically to reduce transmission risk. 1

Asymptomatic individuals in high-risk settings (healthcare workers, food handlers, childcare providers, eldercare workers) should be treated according to local public health guidance. 1

Clostridioides difficile Infection

For confirmed C. difficile-associated diarrhea, vancomycin 125 mg orally four times daily for 10 days achieves clinical success rates of approximately 80%. 5 Clinical success is defined as diarrhea resolution and absence of severe abdominal discomfort by Day 10. 5

Infection Control and Prevention

Hand hygiene is mandatory after toilet use, diaper changes, before and after food preparation, before eating, after handling garbage or soiled laundry, and after animal contact. 1, 2

• Use soap and water or alcohol-based sanitizers, with product selection based on suspected pathogen. 1
• Ill patients should avoid swimming, water-related activities, and sexual contact while symptomatic. 1
• Implement contact precautions (gloves and gowns) in healthcare settings. 1

Common Pitfalls to Avoid

• Never give antimotility agents to children or patients with bloody/febrile diarrhea—this can precipitate toxic megacolon. 1, 4
• Never use routine antimicrobials for acute watery diarrhea—this promotes resistance without benefit. 1, 2
• Never withhold food during diarrheal episodes—early realimentation is beneficial. 1, 3
• Never neglect rehydration while focusing on antimicrobial therapy—dehydration is the primary threat. 1, 3
• Never use antimicrobials in STEC infections—this increases HUS risk. 1, 2